#include <stdio.h>

int main(void)
{
	int i, j;
	double sum = 0;

	for (i = 1, j = 2; i <= 99; i +=2, j += 2)
		sum += 1.0 / i - 1.0 / j;
	printf("sum = %f\n", sum);

	return 0;
}